A Class A precursor is a chemical that can be diverted from legitimate activities to the illegal manufacture of drugs.

In the case of ephedrine, that illegal drug is crystal meth — a powerful psycho-stimulant that, over the past decade, has fuelled a drug crisis in the United States.

The crisis led to sweeping new laws to tightly control access to the key ingredients such as ephedrine.

The Mounties noticed King's business and — according to court documents — so did the U.S. Drug Enforcement Agency.

The DEA was suspicious about ephedrine coming into the States.

The RCMP raided King's businesses and home in November.

"I open up the door and here's a whole bunch of cops," King said.

"And they're saying, ‘We're coming into your house.’ And I'm like this: ‘For what?’ And they were like: ‘For ephedrine.’ And I was like, ‘You've got to be kidding me.’"

There is nothing in the court documents to suggest that King's ephedrine shipments had anything to do with crystal meth.

The issue — according to the police — is that pills were crossing the border illegally.

Investigation underway for months

King and his girlfriend Danielle Rideout live and work together.

The Mounties are looking into both of them, and more than a half dozen of their companies.

At the time of the raids, the RCMP had been investigating for months.

From August to October, police intercepted 44 packages of ephedrine containing 44,700 pills mailed to customers all over the United States. One package was addressed to a person serving on a U.S. military base in Kuwait.

The DEA had earlier seized a package King mailed to New Mexico, saying it violated two state laws.

"I had no issues in shipping to the U.S. and everywhere for 10 years," King said. "So for 10 years I did not receive one notice. I did not receive one document. I did not receive anything saying that what I was doing was illegal."

Asked if he checked to see whether he needed a licence, King said: "No, I did not. But I've had that site for, I believe, 10 years and at no point did I receive anything."

CBC News contacted Health Canada to get clarification on the rules for selling any quantity of ephedrine.

The reply: "All individuals or corporations who wish to produce, package, provide or sell, import or export Class A precursors must apply for a licence."

King does not think he’s done anything wrong by selling ephedrine to the U.S.

"Nothing. The only thing I think I did wrong was doing a good job of it …

"If they came to us at any point and said something I was doing was wrong or illegal, I would have stopped. At no point did I receive that."

Discreet packaging

King is proud of what he's built, and says his ephedrine business was above board.

But the RCMP documents suggest King lists the value of the packages he ships below the sales price he advertises online.

The packages are labeled as gifts or supplements instead of ephedrine.

King's web page even offers customers a discreet service with plain, unmarked packaging.

He defends the practice.

"The thing is I would say that a lot of people are probably uncomfortable with having ephedrine shipped to the U.S.," King said.

"But we’ve done nothing wrong in that regard."

But according to court affidavits, the RCMP investigation isn't just confined to the sale of ephedrine.

The filings indicate that the force is also carrying out a "proceeds of crime and money laundering investigation."

In the raid on King's house, the Mounties seized computers along with dozens of boxes of invoices and financial documents.

"We kept every single document," King said.

"For Revenue Canada, you have to keep seven years of documents. We kept them. We kept them. We kept every single document. Every single sale. Every single receipt. Because I was not hiding this."

Police also found a lot of money at the house — more than $30,000 in cash that King says is an emergency fund his accountant advised him to have.

"This gym does $1 million in revenue a year," King said. "So is $30,000 in cash sitting somewhere for a $1-million business a big deal? I don’t consider it to be. I mean, my accountant told me to have it, so that’s why I had it. I mean, once again, I did nothing wrong."

Word spread through fitness community

The investigation is ongoing, and King hasn't been charged.

But word of all this has spread through the city and the fitness community.

'It’s been brutal. I've worked very hard to establish my business and to build my brand and to build Heavyweights. I love what I do. It's all I do. And people want to see that go down. I don't know why.'—Rob King

"It’s brutal," King said. "It’s been brutal. I've worked very hard to establish my business and to build my brand and to build Heavyweights. I love what I do. It's all I do. And people want to see that go down. I don't know why."

So what’s next?

"I keep working," King said. "I keep doing what I do, which is train clients, help people get in shape, make their lives better and do what I do. I love business and I love fitness. And I'm not going to stop doing what I do over this — at all. I love what I do."

King says he has stopped selling ephedrine online. He shut it down soon after the raid.

He is, however, in the process of applying for the Class A precursor licence Health Canada says he needs.

Contacted by CBC News, the RCMP declined comment, citing the ongoing nature of their investigation.